Grape IPM in the Northeast

IPM Disease Management Protocols

Postinfection, Primary-Season-Only Spray Protocol
for Concord

Sprays are timed according to the presence of the powdery
mildew (490k pdf file) and black
rot (548k pdf file) inoculum and the occurrence of an infection period. An infection period occurs
under the following conditions: 1) For powdery mildew, approximately 0.1 inch
or more of rain and temperatures equal to or above 50°F, or 2) any amount
of rain and temperatures during the period of leaf wetness that are suitable
for black rot infection (see table 3 below).

Table by R. A Spotts, Ohio State University. Reprinted with
permission.

Monitoring of weather conditions for infection periods should begin at
three inches of shoot growth. Once an infection period for either black
rot or powdery mildew has occurred, the following fungicides should be applied
within 72 hours after the start of the infection period. Nova at 4 oz/A
should be used in combination with an EBDC (Manzate, Dithane, etc.) at 3
lb/A in all prebloom, postinfection sprays. After this fungicide application,
a 14-day interval should pass before additional treatments are considered.
Infection periods that occur within that interval should be ignored. Weather
monitoring should continue in order to time fungicide applications in accordance
with infection periods until the supply of black rot ascospores is nearly
exhausted, or when berries are 5 mm in diameter (pea-size). The Nova label
states that a maximum of 21 days of protection is provided for powdery mildew.
If no infection periods have been recorded after 20 days and berries have
not reached 5mm in size, another Nova application at 4 oz/A should be applied.
Continue monitoring for infection periods after 14 days or until berries
reach 5mm in size.

One disadvantage of the postinfection program is that there are no postinfection
fungicides that will manage Phomopsis
Cane and Leaf Spot
(277k pdf file) or downy
mildew (300k pdf file), and protectant applications for them are not a part of the protocol.
Phomopsis and downy mildew can be maintained at low levels using this protocol
in low-inoculum vineyards and in years that do not favor severe infections.
However, if a vineyard has a history of severe Phomopsis or downy mildew
infections, a primary-season protectant disease management strategy should
be used.

An example of how the postinfection disease management protocol has been used
successfully in grower vineyards is illustrated by figure 4 below. This
figure shows infection periods and wetting periods as they were recorded
during the 1994 growing season at the Lake Erie Center for Grape Research
and Extension (LECGRE), Fredonia, New York. Wetting periods are rain
events that produce leaf wetness but do not provide conditions necessary
for disease germination and infection. Bud break occurred on May 2,
with 3 inches of shoot growth in some areas by May 5. Three inches of
shoot growth is the "trigger" to start monitoring for infection
periods in Concord vineyards with a history of black rot or powdery
mildew. Vineyards without a history of problems with these diseases
can wait until 10 inches of shoot growth.

An infection period for powdery mildew occurred on May 5. This required
a tank-mix application of Nova at 4 oz/A and an EBDC (Manzate, Dithane,
etc.) at 3 lb/A within 72 hours after the 9 p.m. start of the infection
period on May 5. As shown in figure 4, a fungicide application was made
on May 6. Four ounces of Nova provides 14 days' protection against black
rot and powdery mildew. While the Nova label states that 21 days' protection
is provided for powdery mildew, monitoring is resumed after 14 days due
to the loss of protection for black rot. Therefore, no monitoring for infection
periods was required until May 21.

An infection period occurred on May 26, resulting in the need for a second
Nova/EBDC application. Once again, no monitoring took place for 14 days.
On the fifteenth day following the fungicide application, weather conditions
were again monitored for conditions suitable for infection by black rot
or powdery mildew. An infection period occurred on June 13, followed by
a third Nova/EBDC application on June 14. The official date of bloom at
the LECGRE was June 19. This date has significance because some processors
allow EBDCs to be used only from bud break to the time just prior to bloom.
As shown in figure 4, the June 14 fungicide application provided protection
to the shoots and leaves for the bloom and immediate postbloom period, during
which six of the seven late-June infection periods occurred.

The seventh infection period on June 29 required a fungicide application
of Nova at 4 oz/A and Ferbam at 3 lb/A (used due to the restriction on EBDCs).
This was the fourth and final spray, as this application provided protection
past the time of pea-size berries.

When the growth stage of pea-size berries is reached, primary inoculum
of black rot and powdery mildew are expended. With good early-season protection,
little or no primary infection should occur. This should, in turn, severely
limit the amount of secondary inoculum. Concord growers using the postinfection
spray program during the 1990-1994 growing seasons achieved management of
powdery mildew and black rot equal to or better than that provided by their
conventional fungicide programs.

Figure 5 (below) shows a typical grower adaptation to the postinfection
disease management protocol. Many Concord vineyards historically have low
levels of black rot and powdery mildew at harvest and therefore low levels
of overwintering inoculum. Growers with these vineyards do not need to start
applying fungicides until the 10-inch growth stage. In figure 5 growers
have waited until the 10- to 12-inch shoot growth stage to begin monitoring
for black rot or powdery mildew infection periods. An infection period occurred
on May 15, followed by an extended wetting period - but not an infection
period - caused by sporadic rainfall on May 16. A Nova/EBDC fungicide application
was made on May 17. Monitoring of infection periods began June 1, detection
occurred on June 6, and another Nova/EBDC application was made on June 7.

An infection period on June 23 resulted in a third fungicide application of
Nova and Ferbam. While this application only provided protection against
powdery mildew and black rot until July 9, there were no more infection
periods detected before the growth stage of pea-size berries was attained
on July 10. Similar postinfection programs starting at 10 inches of
shoot growth have been used by growers in the Lake Erie region and have
provided equal or improved protection against powdery mildew and black
rot when compared to their conventional disease management programs
during the 1990-1994 growing seasons.

Postinfection Spray Protocol for Niagara
and
Certain Hybrid Varieties

This program is useful in varieties that have a susceptibility to black
rot and powdery mildew similar to that of Concord, but with an increased
susceptibility to downy mildew and/or Botrytis. The postinfection, primary-season
program will be the same as that used for Concord. This program is to be
used until the prebloom period. (Depending on weather and growth conditions,
the prebloom period could be anywhere from 3 to 10 days prior to bloom.)
Sprays are timed using the Spotts
Chart for black rot or the powdery mildew model of at least 0.1 inch
of rain at a temperature of 50°F or higher.

First SprayStarting at three inches of shoot growth, weather is monitored, and
Nova is applied at 4 oz/A within 72 hours after the start of an infection
period for black rot or powdery mildew (as determined by the Spotts
Chart for black rot or the powdery mildew model of 0.1 inch of rain
and temperature of 50°F or above).

Second SprayAfter waiting 14 days, monitoring of weather conditions for black rot
or powdery mildew infection periods begins. When either occurs, Nova is
applied at 4 oz/A. Do not allow more than 21 days to elapse between the
first and second fungicide applications. Label restrictions do not allow
for more than 21 days to elapse between applications of Nova.

Other Prebloom SpraysSame protocol is followed as for the second spray.

Immediate Prebloom PeriodThis application will be a postinfection application of Nova (4 oz/A)
+ mancozeb (3 lb/A) or as a protectant application if no infection periods
for black rot or powdery mildew have occurred immediately prior to bloom.
In other words, a Nova + mancozeb spray needs to be applied prior to bloom
for downy mildew, powdery mildew, and black rot protection through bloom.
Ridomil MZ may be substituted for mancozeb for this spray.

Postbloom SpraysThese will be driven by a downy mildew sporulation model, if available,
and the occurrence of black rot or powdery mildew infection periods. The
postinfection disease program will be terminated when berries have reached
pea-size (5mm). Neogen
and METOS weather equipment have downy mildew sporulation models available.
If no downy mildew models are available and conditions exist for downy mildew
infection, fungicides should be applied based on a protectant program. Applications
of an EBDC, captan, Ridomil/MZ 58, Ridomil/ copper, or copper + lime can
be used for downy mildew. Sulfur, copper + lime, JMS Stylet Oil, or a sterol
inhibitor can be used for powdery mildew. Check processor restrictions before
making an EBDC or captan application. Do not apply Nova, Bayleton, or Rubigan
in vineyards with existing severe powdery mildew infections.

Supplemental Management of Botrytis on Susceptible Cultivars or in Vineyards
With a History of Botrytis Infection

Bloom: apply Rovral at 1.5 lb/A only if average temperature is greater
than 60°F, and there is abundant rainfall.

This program is designed to provide excellent management of primary infections
of powdery mildew, black rot, and downy mildew, and of fruit and rachis
infections of Phomopsis Cane and Leaf Spot during the period of susceptibility.
This should allow cessation of black rot management after the first postbloom
spray, cessation of Phomopsis sprays, cessation of downy mildew sprays unless
scouting reveals the need to manage additional secondary spread later in
the summer, and relatively inexpensive management of secondary powdery mildew
during the summer. This is also a good resistance management program for
powdery mildew. Midsummer outbreaks of powdery mildew (very unlikely if
protocol is followed) should be responded to with JMS Stylet Oil, not the
sterol-inhibiting fungicides.

First Spray Starting at three inches of shoot growth, monitor weather and apply
Nova at 4 oz/A for black rot and powdery mildew within 72 hours after the
start of a powdery mildew (PM) or black rot (BR) infection period. Add mancozeb
at 3 lb/A if there is a history of Phomopsis (Phom) infection.

Midsummer SpraysApply sulfur for PM at 7- to 14-day intervals through veraison when
needed as indicated by scouting or apply JMS Stylet Oil to eradicate existing
powdery mildew infections. Captan or copper + lime may be used for downy
mildew if scouting indicates a need.

Supplemental Management of Botrytis for Susceptible Cultivars or in Vineyards
With a History of Botrytis Infection

Bloom: apply Rovral at 1.5 lb/A only if average temperature is greater
than 60°F, and there is abundant rainfall.

Primary-Season Protectant Disease Management
Strategy

This protocol can be used in place of the postinfection disease management
protocol for varieties that are susceptible to black rot, Phomopsis Cane
and Leaf Spot, and/or downy mildew, but not powdery mildew. This disease
protocol attempts to greatly reduce the amount of primary infections through
early-season fungicide applications, as does the postinfection protocol,
using a protectant schedule. However, this protocol does not provide management
of powdery mildew prior to the prebloom application. Therefore, it should
not be used in vineyards with a history of powdery mildew infections or
in vineyards with highly susceptible varieties (see table
2, 69k pdf file) for varietal susceptibility to this disease). This protocol will result
in four fungicide applications being made each year.

Timing

Fungicide Applied

3 inches of shoot growth

EBDC

14 days after first application

EBDC

14 days after second application (prebloom)

SI* + EBDC

14 days after third application

SI* + EBDC or Ferbam or Ziram

* SI = sterol inhibitor (Bayleton, Nova, or Rubigan).
Rubigan should not be used as the sole fungicide for management of black
rot under conditions of heavy disease pressure.

NYS IPM on:

These pages are maintained by the New York State IPM Program, part of Cornell Cooperative Extension. All material is protected by Section 107 of the 1976 copyright law. Copyright is held by Cornell University and the New York State IPM Program.